Annotation of embedaddon/libnet/sample/gre.c, revision 1.1
1.1 ! misho 1: /*
! 2: *
! 3: * libnet 1.1
! 4: * Build a GRE packet
! 5: * To view: tcpdump -s 0 -n -X -vvv proto gre
! 6: *
! 7: * Copyright (c) 2003 Frédéric Raynal <pappy@security-labs.org>
! 8: * All rights reserved.
! 9: *
! 10: *
! 11: * KNOWN BUG
! 12: * the encapsulated headers have wrong checksums. I guess this is due to
! 13: * the one pass libnet_pblock_coalesce() which is really to complicated :(
! 14: *
! 15: *
! 16: * Default packet:
! 17: * # ./gre -d 1.2.3.4
! 18: * libnet 1.1 packet shaping: GRE 1701 [link]
! 19: * Wrote 78 byte GRE packet; check the wire.
! 20: *
! 21: * 18:58:12.112157 192.168.1.2 > 1.2.3.4: gre 198.35.123.50.1234 > 103.69.139.107.53: S [bad tcp cksum 698a!] 16843009:16843009(0) win 32767 (ttl 64, id 242, len 40, bad cksum 0!) (ttl 255, id 255, len 64)
! 22: * 0x0000 4500 0040 00ff 0000 ff2f f4df c0a8 0102 E..@...../......
! 23: * 0x0010 0102 0304 0000 0800 4500 0028 00f2 0000 ........E..(....
! 24: * 0x0020 4006 0000 c623 7b32 6745 8b6b 04d2 0035 @....#{2gE.k...5
! 25: * 0x0030 0101 0101 0202 0202 5002 7fff 6666 0000 ........P...ff..
! 26: *
! 27: * Packet with a computed checksum
! 28: * # ./gre -d 1.2.3.4 -c 0
! 29: * libnet 1.1 packet shaping: GRE 1701 [link]
! 30: * Wrote 82 byte GRE packet; check the wire.
! 31: *
! 32: * 18:58:22.587513 192.168.1.2 > 1.2.3.4: gre [Cv0] C:7c62 198.35.123.50.1234 > 103.69.139.107.53: S [bad tcp cksum 698a!] 16843009:16843009(0) win 32767 (ttl 64, id 242, len 40, bad cksum 0!) (ttl 255, id 255, len 68)
! 33: * 0x0000 4500 0044 00ff 0000 ff2f f4db c0a8 0102 E..D...../......
! 34: * 0x0010 0102 0304 8000 0800 7c62 0000 4500 0028 ........|b..E..(
! 35: * 0x0020 00f2 0000 4006 0000 c623 7b32 6745 8b6b ....@....#{2gE.k
! 36: * 0x0030 04d2 0035 0101 0101 0202 0202 5002 7fff ...5........P...
! 37: * 0x0040 6666 0000 ff..
! 38: *
! 39: *
! 40: * Packet with a forced checksum
! 41: * # ./gre -d 1.2.3.4 -c 6666
! 42: * libnet 1.1 packet shaping: GRE 1701 [link]
! 43: * Wrote 68 byte GRE packet; check the wire.
! 44: *
! 45: * 19:04:12.108080 192.168.1.2 > 1.2.3.4: gre [Cv0] C:1a0a 198.35.123.50.1234 > 103.69.139.107.53: S [bad tcp cksum 698a!] 16843009:16843009(0) win 32767 (ttl 64, id 242, len 40, bad cksum 0!) (ttl 255, id 255, len 68)
! 46: * 0x0000 4500 0044 00ff 0000 ff2f f4db c0a8 0102 E..D...../......
! 47: * 0x0010 0102 0304 8000 0800 1a0a 0000 4500 0028 ............E..(
! 48: * 0x0020 00f2 0000 4006 0000 c623 7b32 6745 8b6b ....@....#{2gE.k
! 49: * 0x0030 04d2 0035 0101 0101 0202 0202 5002 7fff ...5........P...
! 50: * 0x0040 6666 0000 ff..
! 51: *
! 52: *
! 53: *
! 54: *
! 55: * Redistribution and use in source and binary forms, with or without
! 56: * modification, are permitted provided that the following conditions
! 57: * are met:
! 58: * 1. Redistributions of source code must retain the above copyright
! 59: * notice, this list of conditions and the following disclaimer.
! 60: * 2. Redistributions in binary form must reproduce the above copyright
! 61: * notice, this list of conditions and the following disclaimer in the
! 62: * documentation and/or other materials provided with the distribution.
! 63: *
! 64: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
! 65: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 66: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 67: * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
! 68: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 69: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 70: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 71: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 72: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 73: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 74: * SUCH DAMAGE.
! 75: *
! 76: */
! 77:
! 78: #if (HAVE_CONFIG_H)
! 79: #include "../include/config.h"
! 80: #endif
! 81: #include "./libnet_test.h"
! 82:
! 83:
! 84: void
! 85: usage(char *prog)
! 86: {
! 87: fprintf(stderr, "Usage: %s\n", prog);
! 88: fprintf(stderr, "\t IP options: -d <dst ip> [-s src ip]\n");
! 89: fprintf(stderr, "\t GRE options: [-v] set RFC 2637 mode (PPP in GRE) (default is RFC 1701 for IP in GRE)\n");
! 90: fprintf(stderr, "\t\t RFC 1701 options (IP in GRE):\n");
! 91: fprintf(stderr, "\t\t [-c sum] [-r routing] [-k key] [-n seqnum]\n");
! 92: fprintf(stderr, "\t\t IP in GRE options: [-S src ip] [-D dst ip]\n");
! 93: fprintf(stderr, "\t\t RFC 2637 options (PPP in GRE):\n");
! 94: fprintf(stderr, "\t\t [-a ack]\n");
! 95:
! 96: exit(1);
! 97: }
! 98:
! 99: /*
! 100: * ---------------------------------
! 101: * | Delivery Header |
! 102: * ---------------------------------
! 103: * | GRE Header |
! 104: * ---------------------------------
! 105: * | Payload packet |
! 106: * ---------------------------------
! 107: */
! 108: int
! 109: main(int argc, char *argv[])
! 110: {
! 111: char c;
! 112: libnet_t *l;
! 113: char errbuf[LIBNET_ERRBUF_SIZE];
! 114: u_long src_ip = 0, dst_ip = 0, gre_src_ip = 0, gre_dst_ip = 0;
! 115: u_short checksum = 0, offset = 0;
! 116: u_char *routing = NULL;
! 117: u_long key = 0, seq = 0;
! 118: u_short gre_flags = 0;
! 119: u_long len;
! 120: u_long size = 0;
! 121: libnet_ptag_t t;
! 122:
! 123: printf("libnet 1.1 packet shaping: GRE [link]\n");
! 124:
! 125: /*
! 126: * Initialize the library. Root priviledges are required.
! 127: */
! 128: l = libnet_init(
! 129: LIBNET_LINK, /* injection type */
! 130: NULL, /* network interface */
! 131: errbuf); /* error buffer */
! 132:
! 133: if (!l)
! 134: {
! 135: fprintf(stderr, "libnet_init: %s", errbuf);
! 136: exit(EXIT_FAILURE);
! 137: }
! 138:
! 139: /*
! 140: * parse options
! 141: */
! 142: while ((c = getopt(argc, argv, "d:s:D:S:c:r:k:n:va:")) != EOF)
! 143: {
! 144: switch (c)
! 145: {
! 146:
! 147: case 'd':
! 148: if ((dst_ip = libnet_name2addr4(l, optarg, LIBNET_RESOLVE)) == -1)
! 149: {
! 150: fprintf(stderr, "Bad destination IP address: %s\n", optarg);
! 151: exit(EXIT_FAILURE);
! 152: }
! 153: break;
! 154: case 's':
! 155: if ((src_ip = libnet_name2addr4(l, optarg, LIBNET_RESOLVE)) == -1)
! 156: {
! 157: fprintf(stderr, "Bad source IP address: %s\n", optarg);
! 158: exit(EXIT_FAILURE);
! 159: }
! 160: break;
! 161: case 'D':
! 162: if ((gre_dst_ip = libnet_name2addr4(l, optarg, LIBNET_RESOLVE)) == -1)
! 163: {
! 164: fprintf(stderr, "Bad destination IP address (GRE): %s\n", optarg);
! 165: exit(EXIT_FAILURE);
! 166: }
! 167: break;
! 168: case 'S':
! 169: if ((gre_src_ip = libnet_name2addr4(l, optarg, LIBNET_RESOLVE)) == -1)
! 170: {
! 171: fprintf(stderr, "Bad source IP address (GRE): %s\n", optarg);
! 172: exit(EXIT_FAILURE);
! 173: }
! 174: break;
! 175: case 'c':
! 176: checksum = atoi(optarg);
! 177: gre_flags|=GRE_CSUM;
! 178: break;
! 179: case 'r':
! 180: routing = optarg;
! 181: gre_flags|=GRE_ROUTING;
! 182: break;
! 183: case 'k':
! 184: key = atoi(optarg);
! 185: gre_flags|=GRE_KEY;
! 186: break;
! 187: case 'n':
! 188: seq = atoi(optarg);
! 189: gre_flags|=GRE_SEQ;
! 190: break;
! 191: case 'v':
! 192: gre_flags|=(GRE_VERSION_1|GRE_KEY);
! 193: break;
! 194: case 'a':
! 195: if (! (gre_flags & GRE_VERSION_1))
! 196: usage(argv[0]);
! 197: seq = atoi(optarg); /* seq in v0 is ack in v1 */
! 198: gre_flags|=GRE_ACK;
! 199: break;
! 200: default:
! 201: exit(EXIT_FAILURE);
! 202: }
! 203: }
! 204:
! 205: /*
! 206: * check options
! 207: */
! 208: if (!dst_ip)
! 209: {
! 210: usage(argv[0]);
! 211: }
! 212:
! 213: if (!src_ip)
! 214: {
! 215: src_ip = libnet_get_ipaddr4(l);
! 216: }
! 217:
! 218: if (!gre_dst_ip)
! 219: {
! 220: gre_dst_ip = libnet_get_prand(LIBNET_PRu32);
! 221: }
! 222:
! 223: if (!gre_src_ip)
! 224: {
! 225: gre_src_ip = libnet_get_prand(LIBNET_PRu32);
! 226: }
! 227:
! 228:
! 229: if ( (gre_flags & GRE_VERSION_MASK) == 0)
! 230: {
! 231: /*
! 232: * Build a TCP/IP packet embedded in GRE message
! 233: */
! 234: size = LIBNET_TCP_H;
! 235: t = libnet_build_tcp(
! 236: 1234, /* source port */
! 237: 53, /* destination port */
! 238: 0x01010101, /* sequence number */
! 239: 0x02020202, /* acknowledgement num */
! 240: TH_SYN, /* control flags */
! 241: 32767, /* window size */
! 242: 0, /* checksum */
! 243: 0, /* urgent pointer */
! 244: size, /* TCP packet size */
! 245: NULL, /* payload */
! 246: 0, /* payload size */
! 247: l, /* libnet handle */
! 248: 0); /* libnet id */
! 249: if (t == -1)
! 250: {
! 251: fprintf(stderr, "Can't build TCP header (GRE): %s\n", libnet_geterror(l));
! 252: goto bad;
! 253: }
! 254:
! 255: size += LIBNET_IPV4_H;
! 256: t = libnet_build_ipv4(
! 257: size, /* length */
! 258: 0, /* TOS */
! 259: 242, /* IP ID */
! 260: 0, /* IP Frag */
! 261: 64, /* TTL */
! 262: IPPROTO_TCP, /* protocol */
! 263: 0, /* checksum */
! 264: gre_src_ip, /* source IP */
! 265: gre_dst_ip, /* destination IP */
! 266: NULL, /* payload */
! 267: 0, /* payload size */
! 268: l, /* libnet handle */
! 269: 0); /* libnet id */
! 270: if (t == -1)
! 271: {
! 272: fprintf(stderr, "Can't build IP header (GRE): %s\n", libnet_geterror(l));
! 273: goto bad;
! 274: }
! 275: }
! 276:
! 277: if ( (gre_flags & GRE_VERSION_MASK) == 1)
! 278: {
! 279: offset = libnet_get_prand(LIBNET_PRu16);
! 280: if (~gre_flags & GRE_ACK)
! 281: {
! 282: u_char ppp[4] = "\x00\x01"; /* PPP padding */
! 283: checksum = 2; /* checksum is in fact payload_s in PPP/GRE (v1) */
! 284: size = 2;
! 285: gre_flags|=GRE_SEQ;
! 286: key = libnet_get_prand(LIBNET_PRu32);
! 287:
! 288: /*
! 289: * Build a PPP packet embedded in GRE message
! 290: */
! 291: t = libnet_build_data(
! 292: ppp,
! 293: checksum,
! 294: l,
! 295: 0
! 296: );
! 297: if (t == -1)
! 298: {
! 299: fprintf(stderr, "Can't build PPP header (GRE): %s\n", libnet_geterror(l));
! 300: goto bad;
! 301: }
! 302: }
! 303: gre_flags&=~(GRE_CSUM|GRE_ROUTING);
! 304: }
! 305:
! 306: /*
! 307: * Build the GRE message
! 308: */
! 309: if (gre_flags & GRE_ROUTING)
! 310: {
! 311: /* as packet are stacked, start by the last one, ie null sre */
! 312: size += LIBNET_GRE_SRE_H;
! 313: t = libnet_build_gre_last_sre(l, 0);
! 314: if (t == -1)
! 315: {
! 316: fprintf(stderr, "Can't build GRE last SRE header: %s\n", libnet_geterror(l));
! 317: goto bad;
! 318: }
! 319: size += LIBNET_GRE_SRE_H + strlen(routing);
! 320: t = libnet_build_gre_sre(
! 321: GRE_IP, /* address family */
! 322: 0, /* offset */
! 323: strlen(routing), /* routing length */
! 324: routing, /* routing info */
! 325: NULL, /* payload */
! 326: 0, /* payload size */
! 327: l, /* libnet handle */
! 328: 0); /* libnet id */
! 329: if (t == -1)
! 330: {
! 331: fprintf(stderr, "Can't build GRE last SRE header: %s\n", libnet_geterror(l));
! 332: goto bad;
! 333: }
! 334: }
! 335:
! 336: len = libnet_getgre_length(gre_flags);
! 337: size += len;
! 338: t = libnet_build_gre(
! 339: gre_flags, /* flags & version */
! 340: (gre_flags & GRE_VERSION_1 ? GRE_PPP : GRE_IP), /* type */
! 341: checksum, /* v0: checksum / v1: payload_s */
! 342: offset, /* v0: offset / v1: callID */
! 343: key, /* v0: key / v1: seq bum */
! 344: seq, /* v0: seq num / v1: ack */
! 345: size, /* length */
! 346: NULL, /* payload */
! 347: 0, /* payload size */
! 348: l, /* libnet handle */
! 349: 0); /* libnet id */
! 350: if (t == -1)
! 351: {
! 352: fprintf(stderr, "Can't build GRE header: %s\n", libnet_geterror(l));
! 353: goto bad;
! 354: }
! 355:
! 356:
! 357: /*
! 358: * Build the "real" IP header
! 359: */
! 360: size+=LIBNET_IPV4_H;
! 361: t = libnet_build_ipv4(
! 362: size, /* length */
! 363: 0, /* TOS */
! 364: 255, /* IP ID */
! 365: 0, /* IP Frag */
! 366: 255, /* TTL */
! 367: IPPROTO_GRE, /* protocol */
! 368: 0, /* checksum */
! 369: src_ip, /* source IP */
! 370: dst_ip, /* destination IP */
! 371: NULL, /* payload */
! 372: 0, /* payload size */
! 373: l, /* libnet handle */
! 374: 0); /* libnet id */
! 375: if (t == -1)
! 376: {
! 377: fprintf(stderr, "Can't build IP header (GRE): %s\n", libnet_geterror(l));
! 378: goto bad;
! 379: }
! 380:
! 381: t = libnet_autobuild_ethernet(
! 382: "11:11:11:11:11:11", /* ethernet destination */
! 383: ETHERTYPE_IP, /* protocol type */
! 384: l); /* libnet handle */
! 385: if (t == -1)
! 386: {
! 387: fprintf(stderr, "Can't build ethernet header: %s\n",
! 388: libnet_geterror(l));
! 389: goto bad;
! 390: }
! 391: /*
! 392: * Write it to the wire.
! 393: */
! 394:
! 395: c = libnet_write(l);
! 396: if (c == -1)
! 397: {
! 398: fprintf(stderr, "Write error: %s\n", libnet_geterror(l));
! 399: goto bad;
! 400: }
! 401: else
! 402: {
! 403: fprintf(stderr, "Wrote %d byte GRE packet; check the wire.\n", c);
! 404: }
! 405: libnet_destroy(l);
! 406: return (EXIT_SUCCESS);
! 407: bad:
! 408: libnet_destroy(l);
! 409: return (EXIT_FAILURE);
! 410: }
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